There have been a few patents which teach electronic circuit arrangements exhibiting negative resistance. U.S. Pat. No. 3,358,153, Dec. 12, 1967 (Poo), for example, uses a pair of bipolar transistors of the same conductivity to obtain two terminal negative resistance circuit. A positive feedback in the circuit produces a negative resistance which is essentially ohmic in nature, i.e. an equal negative resistance being developed for very low as well as high frequencies. Its behaviours are defined clearly by the static I-V curve shown in the drawings of the patent.
Canadian Pat. No. 924,390, Apr. 10, 1973 (Stanley) also teaches an electrical network having two terminals and exhibiting negative resistance characteristics. The network includes a JFET and a bipolar transistor in that the JFET controls the bias of the bipolar transistor wherein the I-V characteristics curve contains a region of negative resistance.
In a co-pending application Ser. No. 725,999 filed on Apr. 22, 1985 by the inventor of the present application, two terminal electrical networks exhibiting negative admittance are described as containing two active devices e.g. bipolar junction transistors or field-effect transistors or a combination of both, as in the networks of the above referenced patents. However, unlike the above prior patents the two terminal networks of the said pending application use two active devices which are always of opposite conductivities to each other irrespective of the kind of active devices used.
The present invention relates to an electrical network which uses one active device, i.e., bipolar junction transistor or field-effect transistor.
Unlike the patents mentioned above and the co-pending application filed by the inventor, a negative admittance is obtained without the use of positive feedback.
Instead, negative admittance is obtained by phase shifting the AC input current with respect to the AC voltage, applied to the input terminals.
Like the two terminal networks of the co-pending application the three terminal networks of the present application are very versatile in that by selecting the kinds of active devices and the choice of the various circuits components, a wide range of operating characteristics can be obtained. The three terminal networks of the present application can operate as the Esaki diode over a wide range of frequencies.